Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Schedule of Cash and Cash Equivalents [Table Text Block]

	December 31, 2022		December 31, 2021
BioLargo, Inc. and subsidiaries	$	1,685	$	941
Clyra Medical Technologies, Inc.		166		21
Total	$	1,851	$	962

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

	December 31, 2022			December 31, 2021
Customer A		47	%		<10	%
Customer B		10	%		<10	%
Customer C		<10	%		14	%
Customer D		<10	%		11	%
Customer E		<10	%		11	%

	December 31, 2022			December 31, 2021
Customer A		24	%		<10	%
Customer F		<10	%		32	%
Customer G		<10	%		12	%

Schedule of Inventory, Current [Table Text Block]

	December 31, 2022		December 31, 2021
Raw material	$	46	$	108
Finished goods		74		133
Total	$	120	$	241

Schedule of Other Assets, Noncurrent [Table Text Block]

	December 31, 2022		December 31, 2021
Patents	$	34	$	34
Security deposits		36		35
Tax credit receivable		54		—
Total	$	124	$	69

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	2022								2021
	Non Plan				2018 Plan				Non Plan				2018 Plan
Risk free interest rate	2.32	–	3.83	%	2.32	–	3.83	%	1.49	–	1.73	%	0.93	–	1.73	%
Expected volatility	114	–	117	%	114	–	117	%	118	–	124	%	118	–	124	%
Expected dividend yield	—				—				—				—
Forfeiture rate	—				—				—				—
Life in years	10				10				10				10